Pregnancy outcome in natural family planning users: cohort and case-control studies evaluating safety

Conceptions involving aging gametes are of relevance to natural family planning (NFP) because women using NFP to avoid pregnancy abstain from intercourse during the fertile time of the cycle. To help verify the safety of pregnancies occurring among NFP practitioners, our group has, since 1986, conducted a large cohort study involving six experienced NFP centers. Timing of conception was determined from NFP charts, in which women recorded days on which intercourse occurred. The number of days from the most probable conception intercourse to probable day of ovulation was first determined, and used as an estimate of the time gametes remained in the genital tract before fertilization. Several studies have already been completed, cohort as well as case-control in nature.

Thalidomide, a current teratogen in South America

Thalidomide, mainly used for the treatment of leprosy, is a current teratogen in South America, and it is reasonable to assume that at present this situation is affecting many births in underdeveloped countries. Moreover, the potential re-marketing of thalidomide for the treatment of a large variety of diseases may extend the problem to the developed world. When the drug is available, the control of its intake during early pregnancy is very difficult since most pregnancies are unintended. The ongoing occurrence of thalidomide embryopathy cases went undetected by the ECLAMC, due to several factors: (1) low populational coverage through this monitoring system; (2) pre-existence of the teratogen with its effects present in both baseline (expected) and monitored (observed) materials; and (3) lack of a defined phenotype to be monitored. Thus, if thalidomide re-enters the market throughout the world, due to the wide range of new applications, occurrence of phocomelia alone might not be sufficient to detect its effects. By a case-reference approach, the ECLAMC registered 34 thalidomide embryopathy cases born in South America after 1965 whose birthplaces correspond to endemic areas for leprosy. Phocomelia was found in five of eleven fully described cases. Thus, phocomelia alone is neither specific nor sufficient to serve as a suitable phenotype to survey the teratogenic effects of thalidomide. Therefore, a thalidomide-like phenotype, defined as any bilateral upper and/or lower limb reduction defect of the preaxial and/or phocomelia types, should be included in the routine surveillance of birth defects in all programmes.

Epidemiological analysis of rare polydactylies

This work includes all cases with extra digits (polydactyly) registered from a birth sample of over four million births aggregated from two comparable birth series: the Latin-American Collaborative Study of Congenital Malformations: ECLAMC (3,128,957 live and still births from the 1967 to 1993 period), and the Spanish Collaborative Study of Congenital Malformations: ECEMC (1,093,865 livebirths from April 1976 to September 1993, and 7,271 stillbirths from January 1980 to September 1993). All but 2 of 6,912 registered polydactyly cases fit well into one of the following 11 preestablished polydactyly types (observed number of cases in parentheses): Postaxial hexadactyly (5,345), Preaxial-I hexadactyly (1,018), Seven or more digits (57), synpolydactyly (15), crossed polydactyly (45), 1st digit triphalangism (33), 2nd digit duplication (39), 3rd digit duplication (18), 4th digit duplication (22), Haas polysyndactyly (3), and high degree of duplication (4). The birth prevalence rates observed in both series were similar except for postaxial polydactyly, which was more frequent in the ECLAMC (150.2/100,000) than in the ECEMC (67.4/100,000), as expected due to the higher African Black ethnic extraction of the South-American than of the Spanish populations. This similar frequency for the rare polydactylies (5.4 per 100,000 in South America and 5.7 in Spain), and for each one of the 9 categories, suggests that the values reported here are valid for most populations. The rare polydactylies are frequently syndromal: one third of them (77/236) were found in association with other congenital anomalies, 11.0% (26/236) in MCA cases and 21.6% (51/236) in recognized syndromes.

Genealogical information and the structure of rural Latin-American populations: reality and fantasy

Genetic data organized in the form of genealogies can provide much information regarding the history and genetic structure of human populations. A large proportion of the population of Latin America is organized in small rural semi-isolated communities, with little immigration, and until the last 50-100 years, little emigration. These communities have a strong sense of their genealogical history, and this "genealogical conscience' is a frequent leitmotif in modern Latin-American literature. In this communication, we compare the characteristics of fictitious genealogies described in two masterpieces of Latin-American literature, García Márquez' Cien Años de Soledad (A Hundred Years of Solitude), and Verissimo's O Tempo e o Vento (Time and the Wind), with one existing well-studied population in Argentina, Aicuña. All three populations exhibit a number of common characteristics, such as histories of long periods of civil war, and large pedigrees with complex paths of inheritance resulting in complex patterns of inbreeding. Genetic themes common to all three are: (1) the use of genealogical records to substantiate the property of the land or the political power of a kinship; (2) the genealogical registry of biological descendants, independent of their legal or marital status in the clan; (3) the existence of pedigrees of the aristocratic branches in the same kindreds, which illustrate the legal principle of primogeniture; (4) the value of last names as indicators of kinships and the extent of genetic isolation, and (5) the awareness of the deleterious consequences of consanguinity.

VACTERL association, epidemiologic definition and delineation

This study departed from a preconceived definition of VACTERL, including more than one of these six anomalies in the same infant: V (vertebral anomalies), A (anal atresia), C (congenital heart disease), TE (tracheoesophageal fistula or esophageal atresia), R (reno-urinary anomalies), and L (radial limb defect). Under this definition, 524 infants were ascertained by ECLAMC from almost 3,000,000 births examined from 1967 through 1990. Observed association rates among VACTERL components as well as between VACTERL and other defects were compared against randomly expected values obtained from 10,084 multiply malformed infants (casuistic method) from the same birth sample. Conclusions were: 1) Cardiac defects are not a part of VACTERL. 2) Single umbilical artery, ambiguous genitalia, abdominal wall defects, diaphragmatic hernia, and anomalies that are secondary to VACTERL components (intestinal and respiratory anomalies, and oligohydramnios sequence defects) are frequent enough to be considered an "extension" of VACTERL, and cardiac defects should be included in this category. 3) Neural tube defects are negatively associated with VACTERL which could not be explained by selection bias or any other operational artifact. High embryonic lethality or mutually exclusive pathogenetic mechanisms could be suitable explanations. 4) Results were not clear enough to determine whether VACTERL should be defined by at least two or three component defects.

Effect of paternal age in achondroplasia, thanatophoric dysplasia, and osteogenesis imperfecta

The paternal ages of nonfamilial cases of achondroplasia (AC) (n = 78), thanatophoric dysplasia (TD) (n = 64), and osteogenesis imperfecta (OI) (n = 106), were compared with those of matched controls, from an Italian Indagine Policentrica Italiana sulle Malformazioni Congenite and a South American Estudio Colaborativo Latinoamericano de Malformaciones Congénitas series. The degree of paternal age effect on the origin of these dominant mutations differed among the three conditions. Mean paternal age was highly elevated in AC, 36.30 +/- 6.74 years in the IPIMC, and 37.19 +/- 10.53 years in the ECLAMC; less consistently elevated in TD, 33.60 +/- 7.08 years in the IPIMC, and 36.41 +/- 9.38 years in the ECLAMC; and only slightly elevated in OI in the ECLAMC, 31.15 +/- 9.25 years, but not in the IPIMC, 32.26 +/- 6.07 years. Increased maternal age or birth order in these conditions disappeared when corrected for paternal age. Approximately 50% of AC and TD cases, and only 30% of OI cases, were born to fathers above age 35 years. For AC and TD, the increase in relative incidence with paternal age fitted an exponential curve. The variability of paternal age effect in these new mutations could be due, among other reasons, to the high proportion of germ-line mosaicism in OI parents, or to the localization of the AC gene, mapped to the 4p16.3 region, in the neighborhood of an unstable DNA area.

Congenital healed cleft lip

Congenital "healed" cleft lip (CHCL) is an unusual anomaly including a paramedian "scar" of the upper lip, which appears as if a typical cleft lip has been corrected in utero. The CHCL is frequently associated with an ipsilateral notch in the vermilion, and "collapsed" nostril. Twenty-five CHCL cases are presented, eighteen of which were an isolated malformation found among the 3,950,715 births examined in two similar birth defect registries: ECEMC in Spain and ECLAMC in Latin America. Like open cleft lip, of which it seems to be a variant, CHCL is most frequently seen among males (14/18 isolated cases), it preferentially affects the left side (10/18 cases), and it segregated together with cleft lip in one family. The five CHCL cases with other congenital anomalies included: two cases with hydrocephalus, two VACTERL associations, and one atypical oblique facial cleft infant with single umbilical artery. CHCL may result from a defective fusion of the frontonasal and maxillary processes (before week 7 of embryonic life), or from a spontaneously repaired open cleft lip, later on. In either way, these cases heal with a visible scar, and the pre-occurrence of CHCL in two families suggests a familial predisposition to this phenomenon.

Limb reduction defects in South America

OBJECTIVE

Limb reduction defects were considered as possible indicators of environmental teratogenesis; it was suggested that also invasive prenatal procedures could increase the risk for limb reduction defects. The purpose of this work is to give a baseline frequency for limb reduction defects, using data from a population not exposed to prenatal diagnosis procedures.

DESIGN

Using data collected in the period 1967 to 1992 within the frame of the Latin American Collaborative Study of Congenital Malformations which clinically examined 2,917,074 newborn infants, a total of 1715 with limb reduction defects were found. All cases were classified and analysed in 25 categories. Geographic differences in recorded rates were tested by chi 2 for homogeneity. Secular trends were analysed using chi 2 test for linear trends.

RESULTS

The overall birth prevalence rate of limb reduction defects among liveborn infants was 4.91(per 10,000 births) (3.05 for isolated and 1.85 for associated cases). For stillbirths, the total prevalence was 26.73/10,000 (5.53 for isolated and 21.20 for associated cases). The inclusion of the brachydactylies increased those figures to 5.55/10,000 (3.39 for isolated and 2.16 for associated cases), and 27.42, respectively, (5.53 for isolated and 21.89 for associated cases). When isolated and associated cases were considered together, a geographic heterogeneity was found in pre-axial limb reduction defects; there was also some heterogeneity for amputations. A maternal age effect was found for the isolated hypoplasias. Standardising by maternal age, the overall prevalence of limb reduction in liveborn infants was 5.66 per 10,000 (95% CI = 5.38-5.93). An increasing trend was suggested by the isolated form of distal amputations which involved hands, feet, or digits.

CONCLUSIONS

Our data suggest that clustering limb reduction defects in wide groups as transverse and longitudinal may lead to heterogeneous entities. When a possible association is suspected, it would be preferable to present and analyse data in the most discriminant form available. Due to the maternal age effect, it would be advisable to standardise the rates of transversal limb reduction defects by this variable.

Safety of tetanus toxoid in pregnant women: a hospital-based case-control study of congenital anomalies

Reported are the results of the Latin American Collaborative Study of Congenital Malformations (ECLAMC), a hospital-based case-control study of 34,293 malformed and 34,477 matched nonmalformed newborn controls. No statistical differences were found between the malformed and control groups, exposed or not exposed to tetanus toxoid.

International study of sex ratio and twinning of neural tube defects

The goal of this study, based on information collected from eight congenital malformation registry programs around the world, was to analyze sex and twinning of affected infants and fetuses, according to type of neural tube defect (NTD) and other variables. The type of defect and its location, whether it occurred in isolated form or was associated with other malformations, population from which data were retrieved, vital status of the infant, and gestational age of the fetus/infant were considered. The material included 3,416 infants and 168 selectively aborted fetuses with anencephaly, 4,830 infants and 76 fetuses with spina bifida, and 1,022 infants and 19 fetuses with encephalocele. Less than 20% of infants with anencephaly or spina bifida and more than one-third of infants with encephalocele had associated malformations. A female excess was found among all infants with NTD but a male excess in fetuses delivered spontaneously before week 20, indicating selective male late fetal deaths. Sex ratio varied by type of NTD, vital status at birth, presence of associated malformations, and year of birth, with an increasing sex ratio for anencephaly during the 1960s and 1970s. Twinning was positively associated with NTD but the extent of this association varied with NTD type and program, while the distribution by sex type of pair of twin appeared to be similar to that of all births. Twins concordant for anencephaly or encephalocele were mainly found when the defect occurred as part of a syndrome, and only in like-sexed pairs. Twins concordant for spina bifida had the isolated form of the defect and 5 of 6 pairs were like-sexed.(ABSTRACT TRUNCATED AT 250 WORDS)

Apparently normal frequency of congenital anomalies in the highly polluted town of Cubatão, Brazil

Anencephaly is Suspected to cluster in the municipality of Cubatão (Brazil), and is attributed to industrial pollution. We surveyed malformations prospectively in 10,000 births, in 3 consecutive series, corresponding to 3 maternity hospital in Cubatão, under working definitions and norms taken from the ECLAMC (Latin American Collaborative Study of Congenital Malformations). The sample from Cubatão had a higher proportion of black racial ancestry, and lower frequencies for stillbirths and for immediate neonatal death, than in the rest of South America. The birth prevalence of malformations varied between the 3 hospitals in Cubatão, due to differences in ascertainment of minor defects. A higher-than-expected prevalence rate in Cubatão was observed only for postaxial polydactyly, probably due to a higher proportion of black racial ancestry, while lower-than-expected rates were obtained for congenital dislocation of the hip, and for babies with multiple congenital anomalies patterns, both of them attributed to underascertainment of minor defects. These observations do not support the suspicion of an elevated birth prevalence rate for anencephaly, neural tube defects, or any other major congenital malformation in Cubatão.

An international collaborative study of the epidemiology of esophageal atresia or stenosis

Epidemiologic data were analyzed for a total of 2,693 infants with esophageal atresia registered in nine congenital malformation registries around the world. The average recorded prevalence at birth was 2.6 per 10,000 births, with a significant variability among programs--and sometimes within a program--and a maximum prevalence of above 3 per 10,000 births. Clusters of infants with esophageal atresia were observed but may be random. An increasing rate was seen during the period 1965 to 1975 (Norway, South America, Sweden). The type of esophageal atresia was specified in only 439 cases, but no major differences were seen in the epidemiologic characteristics of infants with the most common type (distal fistula) and infants with other types. There was an excess of low birth weight and preterm birth, and infants with esophageal atresia had a birth weight 500 to 1,000 g less than normal infants in each gestational week. There was an excess of twins, apparently mainly or exclusively due to monozygotic twinning, but in only two pairs did both twins have esophageal atresia. There was no effect seen of maternal age, but low parity, irrespective of maternal age, was associated with an increased risk for esophageal atresia. Infant survival varied among programs and depended heavily on associated malformations. Among 1,107 sibs born before the proband and 385 born after the proband, only 25 (1.7%) had a serious malformation; three had esophageal atresia. In 57.3% of the infants with esophageal atresia, no other malformations were present, in 36.4% other major malformations were recorded, and in 6.3% there were chromosomal anomalies. The malformations present associated with esophageal atresia were analyzed: a large proportion entered the constellation sometimes called "caudal mesoderm spectrum of malformations": VATER, Potter, and caudal regression sequences.

Absence of limbs and gross body wall defects: an epidemiological study of related rare malformation conditions

The study is based on almost 10 million births and reports on 215 infants with two unusual malformations: amelia and gross body wall defect. Amelia without body wall defect was present in 116 cases, 67 had body wall defects without amelia, and 32 had both. The total rate was 2.2 per 100,000 births. The infants were divided into five mutually exclusive groups. There were 40 infants (0.4 per 100,000) with agenesis of the body stalk, 18 with amelia and other types of gross body wall defects (0.2 per 100,000), 56 with amelia and malformations other than gross body wall defects (0.6 per 100,000), 41 with amelia (with or without other limb reduction defects) but no nonlimb malformations (0.4 per 100,000), and 60 infants with gross body wall defects of a type other than agenesis of body stalk and without amelia (0.6 per 100,000). A weak trend of decreasing prevalence of these malformations was found during the observation period. Infants with agenesis of the body stalk and infants with amelia combined with other types of gross body wall defects occurred at an increased rate in infants of young women. This maternal age effect is also found with gastroschisis, but not with omphalocele, and may indicate etiological or pathogenetic similarities between gastroschisis and the two former groups of defect. In infants with amelia, additional limb reduction defects could be of any type: transverse, longitudinal, or intercalary. Therefore, amelia may be the end result of different types of disturbances of limb morphogenesis. There was an increased rate of twinning. The relationship with amniotic band syndrome is discussed.

Previous miscarriage and stillbirth as risk factors for other unfavourable outcomes in the next pregnancy

OBJECTIVE

To look for associations between previous fetal loss and fetal malformation or low birthweight in a subsequent pregnancy.

DESIGN

A case-control study with place of birth, time and sex matched controls.

SETTING

72 South American maternity hospitals.

SUBJECTS

18,534 malformed, 1150 non-malformed babies of low birthweight and 16,394 controls. All babies were from mothers with at least one previous pregnancy.

MAIN OUTCOME MEASURES

Frequency of stillbirths and miscarriages in the previous pregnancy and outcome of the index pregnancy.

RESULTS

Multiple malformation, Down's syndrome, anencephaly, spina bifida, pes equinovarus, congenital dislocation of the hip and low birthweight are associated with previous fetal loss.

CONCLUSION

A miscarriage or a stillbirth in a previous pregnancy should be taken into account when the risk of malformations or low birthweight in a subsequent pregnancy is assessed.

An international case-control study on hypospadias. The problem with variability and the beauty of diversity

The paper describes problems and advantages in an international cooperative study of a case-control design, aimed at investigating the possible association between exogenous hormones and hypospadias. The varying degrees of the ascertainment of specific exposures and risk factors, in spite of the use of a standardized questionnaire is illustrated. Definite support for the existence of recall or interviewer bias is presented. On the other hand, the multipopulation design offers possibilities to make use of the diversity of the populations: differences in reproductive patterns and in specific exposures such as drug use, smoking and maternal occupation.

The cyclops and the mermaid: an epidemiological study of two types of rare malformation

Infants with cyclopia or sirenomelia are born at an approximate rate of 1 in 100,000 births. Eight malformation monitoring systems around the world jointly studied the epidemiology of these rare malformations: 102 infants with cyclopia, 96 with sirenomelia, and one with both conditions were identified among nearly 10.1 million births. Maternal age is somewhat increased for cyclopia, indicating the likely inclusion of some chromosomally abnormal infants which were not identified. About half of the infants are stillborn. There is a female excess among infants with cyclopia. Excess twinning occurred for cyclopia and possibly also for sirenomelia. An analysis of associated malformations indicates the similarity between the two conditions, which is in agreement with recent embryological analysis.

Parental fertility and infant hypospadias: an international case-control study

The authors have performed an international case-control study on the significance of exogenous hormones for the origin of hypospadias (Källén et al., 1991 a,b). Using data from this study on 846 infants with isolated hypospadias and equally many controls (next male infant born in the same hospital as the case), variables that might indicate an increased rate of fertility problems in couples who had a boy with hypospadias were studied. Cases had slightly fewer previous pregnancies, there was practically no difference in the rate of previous induced abortions, and no demonstrable difference in menstrual history. Infertility periods of at least 6 months were more likely among cases than controls but the difference did not reach statistical significance in a two-tailed test. There was no demonstrable difference in the time to conceive between cases and controls. The difficulties of directly studying subfertility problems are stressed.

Oral contraceptives in the etiology of isolated hypospadias

With the objective of identifying whether hypospadias in infants is associated with maternal use of oral contraceptives before pregnancy or in early pregnancy, 846 case-control pairs were collected from eight different malformation monitoring programs around the world and mothers were interviewed using structured questionnaires administered after the birth of the infants. There was no difference in the preconceptional use of oral contraceptives between cases and controls, neither with respect to the number of years of oral contraceptive usage nor the time between stopping oral contraceptives and the present pregnancy. To this material was added data on oral contraceptive usage in early pregnancy from two other sources: an ongoing case-control study in Spain (725 infants with hypospadias) and a population-based study in Sweden (631 infants with hypospadias). There was no statistically significant difference in oral contraceptive exposure in early pregnancy between cases and controls. There is no demonstrable association between oral contraceptive use and infant hypospadias.

Stillbirth rate and associated risk factors among 869 750 Latin American hospital births 1982-1986

Fetal death is essential to evaluate perinatal outcome. Accurate stillbirth rate however is difficult to obtain; this is especially so in developing countries. Current information was obtained through a clinical-epidemiological study, ECLAMC, during the 1982-1986 period for a total sample of 869 750 births in 102 hospitals belonging to 11 Latin American countries. The overall stillbirth rate was 2.0%, the highest being in Bolivian (4.4%) and the lowest in Chilean hospitals (0.9%). In all countries there was a high mortality rate among male fetuses. The incidence of stillbirth in multiple pregnancies almost doubled that for singletons. A steady increase with increasing maternal age was observed. The proportion of all births in mothers 35 years of age or older was 10.1%, while the stillbirth proportion among all stillbirths in the same maternal age group was 18.8%. As expected, a higher fetal mortality rate (10.7%) was found in the low birthweight group (less than or equal to 2500 g) than in the group with birthweight greater than 2500 g (0.6%). One out of ten births occurred in the former group. A striking difference was observed in the stillbirth rate between hospitals with free obstetrical care (2.5%) and those in which any type of payment was required (1.4%). Although socioeconomical factors are probably the main factors responsible for fetal death, increased maternal age and a high incidence of low birthweight also contributed greatly to fetal mortality. These risk factors for fetal mortality should be the target of public health actions in these countries.